The present invention relates generally to electrical connectors, and, more particularly, to a programmable keying system for electrical connectors.
Electrical connectors are frequently provided with keying means to permit particular pairs of connectors to properly mate and to prevent the mating of connectors which are not intended to be mated. Keying means are especially useful when a plurality of identical connectors are positioned in close proximity to one another, for example, on a printed circuit board. The incorrect matching of complementary connectors to the connectors on the board can cause serious damage to the circuits improperly connected thereby; and the keying means, by ensuring that each complementary connector will mate with only the correct one of the plurality of connectors on the board, minimizes the risk of improper connection. Keying means are particularly important when the connections are made by untrained personnel as the risk of improper connection is especially great in such circumstances.
Keying systems are known in which a key member is secured in one of a pair of complementary connectors and is adapted to cooperate with an opposing key member secured in the other of the pair of connectors. Each key member is secured in its connector in a selected orientation with respect to its opposing key member so that when the connectors are intended to be mated, extended keying portions on the key members pass by each other during mating to allow the connectors to properly mate. If one of the key members is secured in an incorrect orientation with respect to its opposing key member, however, the extended keying portions on the key members will abut one another during mating to prevent proper mating of the connectors.
Orientation of a key member in a connector is accomplished in several ways. The key member can, for example, be provided with a portion having a polygonal cross-section and be secured within a passageway in the connector having a similar cross-section. The number of sides of the polygonal shape determines the number of possible orientations of the key member.
Many known keying systems for electrical connectors are not fully satisfactory. For example, in connectors containing multiple contacts, many keying systems are capable of preventing incorrectly matched connectors from completely mating with one another, but are not effective in preventing one or more of the individual contacts within the connectors from mating. In many applications, the improper mating of even one pair of contacts in incorrectly matched connectors can close a circuit and cause damage to the circuit.
Also, many known keying systems have a limited number of keying combinations, thus reducing the user's flexibility. In addition, in many known keying systems, the key members are either pre-set in the connector to a particular orientation in the factory necessitating that the customer maintain a larger inventory of differently keyed connectors, or are shipped to the customer disassembled from the connector increasing the number of separate parts which must be shipped and stored.
Many known keying systems are also relatively complex in design and are not readily susceptible to being assembled by automated procedures. This increases manufacturing costs and the cost of the connectors to the ultimate user.